A new strategy for supercritical fluid extraction of copper ions

Complexation combined with supercritical fluid extraction was used to extract Cu(2+). The effects of pressure, temperature, and total volume of CO(2) on the efficiency of extraction were systematically investigated. The extraction recovery was low (57.32%) only by pure supercritical CO(2). Addition of a suitable amount of methanol (v/v=5%) to supercritical CO(2) could enhance the extraction of Cu(2+) (72.69%, relative standard deviation (R.S.D.)=2.12%, n=3), and the recovery increased largely (90.52%, R.S.D.=2.20%, n=3) in the presence of nonionic surfactant Triton X-100. Reverse micelle formation is presented as a new strategy of improving the extraction of metal ions with supercritical CO(2) in this paper.